1. Field of the Invention
The present invention relates to an automotive alternator that includes a rectifier that rectifies alternating current that is generated in a stator into direct current.
2. Description of the Related Art
Examples of known conventional automotive alternators include automotive alternators that include: a rotor that is disposed inside a case and that is fixed to a shaft; a stator that is disposed so as to surround the rotor, in which alternating current is generated by a rotating magnetic field from the rotor; a rectifier that is disposed near an end portion of the shaft and that rectifies the alternating current that is generated by the stator into direct current; and a noise preventing capacitor that is disposed between a positive side and a negative side of the rectifier and that absorbs high-frequency noise that arises during rectification into direct current by the rectifier and adversely affects radio waves (see Patent Literature 1, for example).
Patent Literature 1
Japanese Utility Model Publication No. SHO 58-43423 (Gazette)
In the automotive alternator described above, since rectification ripple voltages arise in the rectifier, one problem has been that current flows through the noise preventing capacitor, and the service life of the noise preventing capacitor is shortened by the generation of heat by the noise preventing capacitor.
The generating capacity of automotive alternators has also increased in recent years, and impedance in connecting wiring between batteries and automotive alternators has also been reduced. For this reason, when an automotive alternator and a battery are finally connected electrically by connecting a negative terminal of the battery and a negative cable from a vehicle body, for example, another problem has been that an inrush current may flow through the noise preventing capacitor, giving rise to sparks between the negative terminal of the battery and a tip portion of the negative cable and degrading the negative terminal of the battery.
An additional problem has been that although abrupt commutation surge voltages can be suppressed by the noise preventing capacitor during rectification, new oscillating waveforms that adversely affect on-board electrical equipment arise.